Component addition polymerization

ABSTRACT

Provided is a process of making a collection of polymeric beads, wherein the beads comprise
         (i) 75 to 99% by weight, based on the weight of the bead, polymerized units of monofunctional vinyl monomer, and   (ii) 1 to 25% by weight, based on the weight of the bead, polymerized units of multifunctional vinyl monomer;   wherein the process comprises   (a) providing an aqueous suspension of monomer droplets comprising initiator, monofunctional vinyl monomer, and multifunctional vinyl monomer;   (b) initiating polymerization of the monomer in the monomer droplets;   (c) while the polymerization of the monomer in the monomer droplets is occurring, adding a monomer feed solution to the suspension

A useful method of producing polymeric beads is suspensionpolymerization, which is a process in which monomer droplets aresuspended in an aqueous medium and then the monomer in the droplets ispolymerized to form polymeric beads. When a mixture of monomers ispresent in the monomer droplet, it is known that the monomers usuallyreact at different rates, thus forming an inhomogeneous polymeric bead.For example, it is contemplated that one or more regions within thedroplet may form copolymer that has a proportion of polymerized units ofthe more-reactive monomer that is higher than the average proportion ofthe more-reactive monomer that is present in the mixture of monomers inthe whole droplet. It is contemplated that such regions that are rich inpolymerized units of the more-reactive monomer would be especiallylikely to form early in the polymerization process. It is furthercontemplated that, later in the polymerization process, regions that arerelatively poor in polymerized units of the more-reactive monomer wouldform. Thus it is contemplated that the resulting polymeric bead would beheterogeneous, with some polymer segments within the bead havingdifferent concentrations of polymerized units of the more-reactivemonomer from other polymer segments. It is anticipated that thisheterogeneity will be detrimental to some of the performance propertiesof the polymeric bead.

It is desired to provide a process for making polymeric beads thatinvolves polymerization of a mixture of monomers that yields polymericbeads in which the distribution of polymerized units of each monomer isrelatively uniform. More generally, it is further desired to provide aprocess by which the extent and nature of the heterogeneity can becontrolled, rather than relying solely on the relative reactivities ofthe monomers to create uncontrolled heterogeneity. It is also desired toprovide a process in which the mass transfer of monomer being fed duringpolymerization into the monomer droplets, where polymerization is takingplace, proceeds efficiently or consistently or both, where“consistently” means that the mass transfer proceeds unusually closelyto identically from one from one batch (i.e., one polymerizationprocess) to another.

In many cases, after polymerization is complete, polymeric beads arefunctionalized. That is, the polymeric beads are subjected to one ormore chemical reactions to attach ionic functional groups, which may beanionic groups or cationic groups, to the polymeric beads.

An important characteristic of polymeric beads is the mechanicalstrength. Mechanical strength may be assessed on the polymeric beadsimmediately after polymerization or may be assessed on functionalizedbeads. The mechanical strength of a bead may be measured directly, forexample by measuring the force necessary to crush the bead. A highercrush strength is desirable, especially for functionalized beads. Also,the mechanical strength may be measured on polymeric beadsfunctionalized with either anionic or cationic groups by exposing thebeads to alternating solutions containing different types of ions.Exposure to these alternating solutions causes osmotic stresses thatcause some polymeric beads to break. It is desirable that as fewfunctionalized beads as possible break from osmotic stress.

U.S. Pat. No. 3,792,029 describes a process of suspension polymerizationin which, during suspension polymerization of a monomer mixture, anemulsion containing the more-reactive monomer is added to the suspensionwhile polymerization is occurring. It is desired to provide a process inwhich neat monomer is added to a suspension polymerization process. Itis also desired to provide polymeric beads having one or more of thefollowing benefits: relatively homogeneous distribution of polymerizedunits of each monomer, high crush strength, consistent and/or efficientmass transfer of feed monomer to monomer droplets, and/or highresistance to osmotic stress.

Additionally, in the process described by U.S. Pat. No. 3,792,029, theemulsion added to the suspension during polymerization contains amixture of the more-reactive monomer and the less-reactive monomer. Inthe mixture added to the suspension described by U.S. Pat. No.3,792,029, there is considerably more (by weight) of the less-reactivemonomer than more-reactive monomer. It is considered that the processdescribed by U.S. Pat. No. 3,792,029 can lead to one or more of thefollowing undesirable effects: the process may cause an increase in thebead size, which places undesirable stress on the polymer network;and/or the process may lead to the formation of inhomogeneity in thestructure of the bead, for example by forming interpenetrating polymernetworks. It is desired to provide a process in which the monomer addedto the suspension during polymerization is 50% or more by weight of themore-reactive monomer. It is also desired to provide a process thatavoids the undesirable effects of the process of U.S. Pat. No.3,792,029.

The following is a statement of the invention.

A first aspect of the present invention is a process of making acollection of polymeric beads, wherein the beads comprise

-   -   (i) 75 to 99% by weight, based on the weight of the bead,        polymerized units of monofunctional vinyl monomer, and    -   (ii) 1 to 25% by weight, based on the weight of the bead,        polymerized units of multifunctional vinyl monomer;    -   wherein the process comprises    -   (a) providing an aqueous suspension of monomer droplets        comprising initiator, monofunctional vinyl monomer, and        multifunctional vinyl monomer;    -   (b) initiating polymerization of the monomer in the monomer        droplets;    -   (c) while the polymerization of the monomer in the monomer        droplets is occurring, adding a monomer feed solution to the        suspension        -   wherein the adding begins at a time when the extent of            polymerization of monomer in the monomer droplets (EXTSTART)            is 0% to 50%, and        -   wherein the adding ends at a time after EXTSTART when the            extent of polymerization of monomer in the monomer droplets            (EXTSTOP) is 5% to 100%;        -   wherein the feed solution comprises monomer in an amount, by            weight based on the weight of the feed solution, of 90% to            100%;        -   wherein the feed solution comprises multifunctional vinyl            monomer in an amount, by weight based on the weight of the            feed solution, of 50% to 100%.

A second aspect of the present invention is a collection of polymericbeads, wherein the beads comprise

-   -   (i) 75 to 99% by weight, based on the weight of the bead,        polymerized units of monofunctional vinyl monomer, and    -   (ii) 1 to 25% by weight, based on the weight of the bead,        polymerized units of multifunctional vinyl monomer;        -   wherein, within each bead, the average concentration of            moles of polymerized units of multifunctional vinyl monomer            per cubic micrometer is MVAV;        -   wherein, within each bead, T1000 is a sequence of 1,000            unique connected polymerized monomer units;        -   wherein, within each T1000, MVSEQ is the weight percent            polymerized units of multifunctional vinyl monomer, based on            the weight of T1000;        -   wherein MVRATIO=MVSEQ/MVAV;        -   and        -   wherein 90% or more of the beads by volume are uniform            beads, wherein a uniform bead is a bead in which 90% or more            of all T1000 sequences has MVRATIO of 1.5 or less.

A third aspect of the present invention is a process for treating water,wherein the water comprises dissolved ions that comprise an undesiredcation, wherein the process comprises

-   -   (a) providing a collection of functionalized polymeric beads        that comprise        -   (i) 75 to 99% by weight, based on the weight of the bead,            polymerized units of monofunctional vinyl monomer, and        -   (ii) 1 to 25% by weight, based on the weight of the bead,            polymerized units of multifunctional vinyl monomer;        -   (iii) functional groups that are bonded to the polymeric            beads and that have charge opposite to the charge of the            undesired ion, and        -   (iv) ions that are not bonded to the polymeric beads and            that have charge the same as the undesired ion;        -   wherein, within each bead, the average concentration of            moles of polymerized units of multifunctional vinyl monomer            per cubic micrometer is MVAV;        -   wherein, within each bead, T1000 is a sequence of 1,000            unique connected polymerized monomer units;        -   wherein, within each T1000, MVSEQ is the weight percent            polymerized units of multifunctional vinyl monomer, based on            the weight of T1000;        -   wherein MVRATIO=MVSEQ/MVAV;        -   and        -   wherein 90% or more of the beads by volume are uniform            beads, wherein a uniform bead is a bead in which 90% or more            of all T1000 sequences has MVRATIO of 1.5 or less;    -   (b) then passing the water through a bed of the collection of        polymeric beads to exchange the undesired ion for the ions (iv),    -   (c) then passing a regeneration solution comprising dissolved        ions (v) of the same species as ions (iv) through the bed of the        collection of polymeric beads to exchange ions (v) for the        undesired ions.

A fourth aspect of the present invention is a process for producing2,2-bis(4-hydroxyphenyl)propane, comprising condensing phenol withacetone in the presence of an acid catalyst to produce dihydric phenol2,2-bis(4-hydroxyphenyl) propane;

wherein the acid catalyst comprises a collection of sulfonated polymericbeads, wherein the sulfonated polymeric beads comprise

-   -   (i) 75 to 99% by weight, based on the weight of the bead,        polymerized units of monofunctional vinyl monomer, and    -   (ii) 1 to 25% by weight, based on the weight of the bead,        polymerized units of multifunctional vinyl monomer;        -   wherein, within each bead, the average concentration of            moles of polymerized units of multifunctional vinyl monomer            per cubic micrometer is MVAV;        -   wherein, within each bead, T1000 is a sequence of 1,000            unique connected polymerized monomer units;        -   wherein, within each T1000, MVSEQ is the weight percent            polymerized units of multifunctional vinyl monomer, based on            the weight of T1000;        -   wherein MVRATIO=MVSEQ/MVAV;        -   and        -   wherein 90% or more of the beads by volume are uniform            beads, wherein a uniform bead is a bead in which 90% or more            of all T1000 sequences has MVRATIO of 1.5 or less.

The following is a detailed description of the invention.

As used herein, the following terms have the designated definitions,unless the context clearly indicates otherwise.

A “polymer,” as used herein is a relatively large molecule made up ofthe reaction products of smaller chemical repeat units. Polymers mayhave structures that are linear, branched, star shaped, looped,hyperbranched, crosslinked, or a combination thereof; polymers may havea single type of repeat unit (“homopolymers”) or they may have more thanone type of repeat unit (“copolymers”). Copolymers may have the varioustypes of repeat units arranged randomly, in sequence, in blocks, inother arrangements, or in any mixture or combination thereof.

Molecules that can react with each other to form the repeat units of apolymer are known herein as “monomers.” The repeat units so formed areknown herein as “polymerized units” of the monomer.

Vinyl monomers have the structure

where each of R¹, R², R³, and R⁴ is, independently, a hydrogen, ahalogen, an aliphatic group (such as, for example, an alkyl group), asubstituted aliphatic group, an aryl group, a substituted aryl group,another substituted or unsubstituted organic group, or any combinationthereof. Vinyl monomers are capable of free radical polymerization toform polymers. Some vinyl monomers have one or more polymerizablecarbon-carbon double bonds incorporated into one or more of R¹, R², R³,and R⁴; such vinyl monomers are known herein as multifunctional vinylmonomers. Vinyl monomers with exactly one polymerizable carbon-carbondouble bond are known herein as monofunctional vinyl monomers.

Styrenic monomers are vinyl monomers in which each of R¹ and R² ishydrogen, R³ is hydrogen or alkyl, and —R⁴ has the structure

where each of R⁵, R⁶, R⁷, R⁸, and R⁹ is, independently, a hydrogen, ahalogen, an aliphatic group (such as, for example, an alkyl group or avinyl group), a substituted aliphatic group, an aryl group, asubstituted aryl group, another substituted or unsubstituted organicgroup, or any combination thereof.

A reaction among monomers to form one or more polymers is referred toherein as a polymerization process.

As used herein, an initiator is a molecule that is stable at ambientconditions but that is capable under certain conditions of producing oneor more fragments that bears a free radical, and that fragment iscapable of interacting with a monomer to start a free radicalpolymerization process. The conditions that cause production of afragment bearing a free radical include, for example, elevatedtemperature, participation in an oxidation-reduction reaction, exposureto ultraviolet and/or ionizing radiation, or a combination thereof.

As used herein the phrase “total monomer” refers to all the monomersused in making a polymer, including monomers that are present wheninitiation of polymerization begins and all of those that may be addedduring the polymerization processes.

A polymer is said herein to contain polymerized units of the monomersused in making the polymer, even if some or all of those polymerizedunits are, after polymerization, altered by the addition of one or morefunctional groups. For example, a copolymer made from styrene and DVB ina weight ratio of styrene:DVB of 90:10 is said to have 90% by weightpolymerized units of styrene. If that copolymer were to be then alteredby reaction with sulfuric acid to replace some of the hydrogen atoms onaromatic rings with sulfonic acid groups, the resulting functionalizedpolymer would still be said to have 90% by weight polymerized units ofstyrene.

As used herein, an inhibitor is a molecule that reacts with a vinylmonomer radical or with the radical on a growing vinyl polymer chain toform a new radical that does not participate in vinyl polymerization.

Macroporous polymeric beads have a porous structure with average porediameter of 20 nm or larger. Pore diameter is measured using theBrunauer-Emmett-Teller (BET) method using nitrogen gas. Macroporouspolymeric beads are normally made by incorporating a porogen intomonomer droplets. The porogen is soluble in the monomer, but the polymerdoes not dissolve in the porogen, so that, as the polymer forms,phase-separated domains of porogen remain. After polymerization, theporogen is removed by evaporation or by washing with solvent. The porousstructure of the polymeric bead is the empty space left when the porogenis removed from its phase-separated domains.

Gel type polymeric beads are made without the use of porogen. The poresin gel type polymeric beads are the free volumes between the atoms inthe entangled, possibly crosslinked polymer chains of the polymericbead. The pores in gel type polymeric beads are smaller than 20 nm. Insome cases, the pores in gel type resins are too small to be detectedusing the BET method.

Two ions or ionic groups are said herein to have the “same” charge ifboth are anionic or if both are cationic, regardless of the magnitude ofthe charge. For example, a sulfonate group (i.e., —SO₃ ⁻) is said tohave the same charge as a carbonate ion (i.e., CO₃ ²⁻). Similarly, twoions or ionic groups are said herein to have “opposite” charge if one isanionic and the other cationic, regardless of the magnitude of thecharge. Carboxylic acid groups are considered to comprise a carboxylateanion and a hydrogen cation, and sulfonic acid groups are considered tocomprise a sulfonate anion and a hydrogen cation).

As used herein, ion exchange is a process in which a solution comes intocontact with an ion exchange resin. Prior to the contact with thesolution, the ion exchange resin has functional groups of a certaincharge, and has ions of the opposite charge associated with thefunctional groups. When the solution comes in contact with the ionexchange resin, some ions in solution become attached to the ionexchange resin by exchanging places with ions of the same charge thathad been associated with the functional groups on the ion exchangeresin.

A compound is said herein to be water-soluble if 5 grams or more of thecompound forms a stable solution in 100 ml of water at 25° C. In thecase of some water-soluble polymers, the water may need to be heatedabove 25° C. in order to make the polymer dissolve, but after cooling to25° C., the solution is stable when held at 25° C.

A suspension is a composition that has particles of one substancedistributed through a liquid medium. The distributed particles may beliquid or solid; distributed liquid particles are called droplets. Themedium is “aqueous” if the medium contains 90% or more water by weight,based on the weight of the medium. A suspension may or may not bestable. That is, the distributed particles may or may not have atendency to settle to the bottom of the container or to float to the topof the container, and mechanical agitation may or may not be required tokeep the particles distributed in the medium.

A polymeric bead is a particle that contains 90% or more by weight,based on the weight of the particle, organic polymer. A polymeric beadis spherical or nearly spherical. A polymeric bead is characterized byits radius. If the bead is not spherical, the radius of the bead istaken herein to be the radius of a “reference sphere,” which is theimaginary sphere that has the same volume as the bead. Whether aparticle is spherical or not is assessed by the “sphericity,”represented by the Greek letter Ψ. For a particle having volume VP, andprincipal axes of length a (long), b (medium) and c (short), thesphericity is

$\Psi = \left( \frac{bc}{a^{2}} \right)^{1/3}$

The unit of volume “cubic micrometer” (abbreviated μm³) as used hereinrefers to the volume of a cube that has edge length of 1 micrometer.

As used herein, “ambient temperature” is synonymous with “roomtemperature” and is approximately 23° C.

A collection of particles has harmonic mean diameter (HMD) defined asfollows:

${HMD} = \frac{n}{\sum_{i = 1}^{n}\left( \frac{1}{d_{i}} \right)}$

where n is the number of particles, and di is the diameter of the i^(th)particle.

Ratios are characterized herein as follows. For example, if a ratio issaid to be 5:1 or higher, it is meant that the ratio may be 5:1 or 6:1or 100:1 but may not be 4:1. To state this characterization in a generalway, if a ratio is said to be X:1 or higher, then the ratio is Y:1,where Y is greater than or equal to X. Similarly, for example, if aratio is said to be 2:1 or lower, it is meant that the ratio may be 2:1or 1:1 or 0.001:1 but may not be 3:1. To state this characterization ina general way, if a ratio is said to be Z:1 or lower, then the ratio isW:1, where W is less than or equal to Z.

The process of the present invention involves monomer droplets thatcontain vinyl monomer and initiator. The following is a description ofthe monomer droplets as they exist prior to initiation ofpolymerization.

Preferably, the amount of monomer in the monomer droplets is, by weightbased on the weight of the droplets, 80% or more; more preferably 90% ormore; more preferably 95% or more.

Preferred vinyl monomers are styrenic monomers, acrylic monomers, andmixtures thereof. Preferably, all the monomers used are selected fromstyrenic monomers, acrylic monomers, and mixtures thereof. Morepreferably, all the monomers used are selected from styrenic monomers.The vinyl monomer includes one or more monofunctional vinyl monomers.Preferred monofunctional vinyl monomers are acrylic and styrenicmonofunctional monomers; more preferred are monofunctional styrenicmonomers; more preferred is styrene. The vinyl monomer also includes oneor more multifunctional vinyl monomers. Preferred multifunctional vinylmonomers are multifunctional styrenic monomers; more preferred isdivinyl benzene. Preferably, the amount of vinyl chloride is, by weightbased on the total weight of all monomers, 0 to 0.1%, more preferably 0to 0.01%; more preferably 0%.

Preferably, the amount of styrenic monomer in the droplets prior toinitiation of polymerization, by weight based on the weight of allmonomers in the droplets, is 50% or higher; more preferably 75% orhigher; more preferably 88% or higher; more preferably 94% or higher;more preferably 97% or higher; more preferably 100%.

Preferably, the amount of monofunctional vinyl monomer in the dropletsprior to initiation of polymerization is, by weight based on the weightof all monomers in the droplets, 75% or more; more preferably 80% ormore; more preferably 85% or more: more preferably 90% or more; morepreferably 94% or more. Preferably, the amount of monofunctional vinylmonomer in the droplets is, by weight based on the weight of allmonomers in the droplets, 99.9% or less; more preferably 99% or less;more preferably 98.5% or less.

Preferably, the amount of multifunctional vinyl monomer in the dropletsprior to initiation of polymerization is, by weight based on the weightof all monomers in the droplets, 0.1% or more; more preferably 1% ormore; more preferably 1.5% or more. Preferably, the amount ofmultifunctional vinyl monomer in the droplets is, by weight based on theweight of all monomers in the droplets, less than 25%; more preferably20% or less; more preferably 15% or less; more preferably 10% or less;more preferably 6% or less.

It is useful to characterize the amount (“MFMPRIOR”) of multifunctionalvinyl monomer in the droplets prior to initiation of polymerization as aweight percentage of the total monomer. Preferably MFMPRIOR is 0.1% ormore; more preferably 0.5% or more; more preferably 1% or more; morepreferably 1.5% or more; more preferably 2% or more. Preferably MFMPRIORis 10% or less; more preferably 8% or less; more preferably 6% or less.

It is also useful to characterize the ratio

MFMRATIO=100*MFMPRIOR/MFMTOTAL

where MFMTOTAL is the total weight percentage of multifunctional monomerused in the entire polymerization process, including multifunctionalmonomer present prior to initiation and multifunctional monomer addedafter initiation. Preferably MFMRATIO is 10% or more; more preferably20% or more; more preferably 30% or more. Preferably MFMRATIO is 80% orless; more preferably 70% or less; more preferably 60% or less.

The process of the present invention involves a suspension of themonomer droplets in an aqueous medium. Preferably, the total amount ofmonomer, by weight based on the total weight of the suspension, is 5% ormore; more preferably 10% or more; more preferably 15% or more.Preferably, the total amount of monomer, by weight based on the totalweight of the suspension, is 55% or less; more preferably 35% or less;more preferably 30% or less.

The monomer droplets contain one or more initiator. Preferred initiatorshave solubility in 100 mL of water at 25° C. of 1 gram or less; morepreferably 0.5 gram or less; more preferably 0.2 gram or less; morepreferably 0.1 gram or less. Preferred are organic peroxide andhydroperoxide initiators; more preferred are peroxide initiators; morepreferred are benzoyl peroxide and derivatives thereof, more preferredis benzoyl peroxide. Preferably, the weight ratio of initiator to totalmonomer is 0.0002:1 or higher; more preferably 0.0005:1 or higher; morepreferably 0.001:1 or higher; more preferably 0.002:1 or higher.Preferably, the weight ratio of initiator to total monomer is 0.02:1 orlower; more preferably 0.01:1 or lower; more preferably 0.007:1 orlower.

The monomer droplets optionally contain one or more porogen. Preferably,little or no porogen is present. That is, preferably either porogen isabsent or else, if present, the amount of porogen is, by weight based onthe weight of monomer droplets, 1% or less; more preferably 0.1% orless. More preferably, no porogen is present in the monomer droplets.

Monomers, as normally supplied by manufacturers, contain relativelysmall amounts of inhibitors, to prevent accidental polymerization duringstorage. Common inhibitors are quinones (for example, 1,4-benzoquinone)and hindered phenols (for example, 4-tert-butylpyrocatechol, also called4-t-butylcatechol).

Preferably, prior to the initiation of polymerization, the monomerdroplets either contain no polymer of any kind or else contain smallamounts of polymer of any kind. That is, if any polymer is present inthe monomer droplets, the total amount of polymer is preferably, byweight based on the weight of the monomer droplets, 0.1% or less.

The aqueous medium preferably contains one or more water-solublepolymer. Water-soluble polymers are considered to stabilize the monomerdroplets against coalescence. Suitable water-soluble polymers may be anyof a wide variety of polymer types. Preferred water-soluble polymers arewater-soluble polyvinyl alcohol polymers, water-soluble derivatives ofcellulose, quaternary ammonium polymers, gelatin, and mixtures thereof.More preferred water-soluble polymers are water-soluble polyvinylalcohol polymers, water-soluble derivatives of cellulose, and mixturesthereof. Among quaternary ammonium polymers, preferred are polymers ofdiallyl dimethylammonium chloride (DADMAC). Among water-solublederivatives of cellulose, preferred are carboxymethyl methylcelluloses.Among polyvinyl alcohol polymers, preferred are those with degree ofhydrolysis of 80% to 90%. Preferably the aqueous medium contains one ormore water-soluble polyvinyl alcohol polymers and one or morewater-soluble derivatives of cellulose.

When one or more water-soluble polymers are used, preferably the totalamount of water-soluble polymers is, by weight based on the weight ofthe aqueous medium, 0.02% or higher; more preferably 0.05% or higher;more preferably 0.1% or higher. When one or more water-soluble polymersare used, preferably the total amount of water-soluble polymers is, byweight based on the weight of the water, 2% or less; more preferably 1%or less; more preferably 0.5% or less.

Also suitable are other methods of stabilizing monomer droplets, whichmay be used instead of one or more water-soluble polymers or in additionto one or more water-soluble polymers. For example, solid particles thatare smaller than the monomer droplets may reside at the surface of thedroplets and stabilize the droplets. One example of such solid particlesis colloidal silica particles.

The aqueous suspension of monomer droplets optionally contains one ormore suspension aids. Suspension aids are considered to stabilize themonomer droplets. Suspension aids may be introduced by adding them tothe aqueous phase or by adding them to the monomer droplets or by acombination thereof. Regardless of how the suspension aid is introduced,a preferred amount of suspension aid, by weight based on the weight ofthe monomer droplets, 0.001% to 0.1%. A preferred suspension aid is4-vinylphenyl boronic acid.

The nature of the step that initiates polymerization depends in part onthe nature of the initiator that is used. For example, when a thermalinitiator is used, initiation conditions involve establishing atemperature above 25° C. that is high enough for a significant fractionof the initiator molecules to decompose to form free radicals. Foranother example, if a photoinitiator is used, initiation conditionsinvolve exposing the initiator to radiation of sufficiently lowwavelength and of sufficiently high intensity for a significant fractionof the initiator molecules to decompose to form free radicals. Foranother example, when the initiator is a redox initiator, initiationconditions involve the presence of sufficiently high concentration ofboth the oxidant and the reductant such that a significant number offree radicals are produced. Preferably, a thermal initiator is used.Preferably, initiation conditions involve temperature of 55° C. orhigher; more preferably 70° C. or higher. That is, preferably thesuspension is provided at a temperature below 40° C., and the initiatorthat is present does not produce significant number of free radicals atthat temperature. Then, preferably, step (b) involves raising thetemperature to initiation conditions.

After step (b), while polymerization is taking place, at any specificmoment, the extent of the free radical polymerization in the vessel thatcontains the suspension may be characterized as follows.

Extent=100*PM/TM

where PM is the mass of polymer formed by the free radicalpolymerization process, and TM is the total mass of monomer that hasbeen added to the vessel up to that moment (including both the initialmonomer droplets and monomer added during the course of thepolymerization).

Prior to the beginning of the polymerization process, droplets arepresent in the suspension, and the droplets contain vinyl monomer andinitiator. Preferably the droplets are distributed throughout theaqueous medium. Preferably the composition of the aqueous mediumcontains water in the amount, by weight based on the weight of theaqueous medium, of 90% or more; more preferably 95% or more; morepreferably 97% or more. Compounds dissolved in the water are consideredto be part of the continuous liquid medium. Preferably, the volumeaverage particle size of the droplets is 50 μm to 1,500 μm.

In the process of the present invention, once the polymerization in themonomer droplets has begun, a feed solution is added to the suspension.The action of adding monomer to the suspension after polymerization hasbegun is known herein as “gradual addition,” or GA. The feed solutionmay be added at any rate. The rate of adding the feed solution may besteady or may be faster at some times than other times. Adding the feedsolution may be accomplished in a single continuous addition (which maybe performed quickly or slowly), or adding the feed solution may beinterrupted one or more times.

Adding the feed solution is begun when the extent of reaction is at apoint herein labeled “EXTSTART.” EXTSTART is between 0% and 50%,inclusive. Preferably, EXTSTART is 40% or lower; more preferably 30% orlower; more preferably 20% or lower; more preferably 10% or lower.

The extent of reaction “EXTSTOP” is the extent of reaction at which thelast of the feed solution is added to the suspension. No feed solutionis added to the suspension after EXTSTOP. EXTSTOP is 5% to 100%.Preferably EXTSTOP is 85% or less. Preferably the quantity

EXTDIFF=EXTSTOP−EXTSTART

is 5% or higher; more preferably 20% or higher; more preferably 50% orhigher; more preferably 60% or higher.

Preferably, the feed solution contains total vinyl monomer of all typesin an amount, by weight based on the weight of the feed solution, 75% ormore; more preferably 85% or more; more preferably 95% or more; morepreferably 99% or more.

The amount of multifunctional monomer in the feed solution ispreferably, by weight based on the weight of the feed solution, 30% ormore; preferably 40% or more; more preferably 45% or more; morepreferably 50% or more; more preferably 55% or more; more preferably 60%or more. When the multifunctional monomer is divinylbenzene (DVB), it issuitable to use an industrial grade of DVB, which is a mixture thatcontains approximately 63% chemically pure DVB by weight andapproximately 37% ethylvinylbenzene (EVB) by weight, with otherimpurities totaling less than 1% by weight. When it is stated here thata composition contains a certain amount of DVB, it is assumed that thecomposition contains, in addition to that stated amount of DVB, EVB at aweight ratio of EVB:DVB of approximately 37:63. When such an industrialgrade of DVB is used, preferably the amount of the industrial grade ofDVB in the feed solution, by weight based on the weight of the feedsolution, is 50% or more; more preferably 60% or more; more preferably70% or more; more preferably 80% or more; more preferably 90% or more;more preferably 95% or more.

Preferably, the feed solution either contains no initiator or elsecontains initiator in an amount, in parts per million by weight, of 100ppm or less; more preferably 10 ppm or less; more preferably 1 ppm orless.

Preferably, the feed solution either contains no water or contains waterin an amount, by weight based on the weight of the feed solution, of 20%or less; more preferably 10% or less; more preferably 3% or less; morepreferably 1% or less; more preferably 0.3% or less; more preferably0.1% or less.

Also envisioned are embodiments (“dispersion feed” embodiments) in whichthe feed solution is replaced by a feed composition that is a dispersionof monomer droplets in an aqueous medium. Such a dispersion may be anytype of, dispersion, including, for example, suspension, emulsion,microemulsion, or nanoemulsion. Such a dispersion optionally containsone or more water-soluble polymer as described above, one or moresurfactant, one or more dispersant, or a mixture thereof. Amongdispersion feed embodiments, preferred are emulsions. Among emulsions,preferred are those that contain one or more anionic surfactant.

In dispersion feed embodiments, the total amount of monomer in the feedcomposition is, by weight based on the weight of the feed composition,5% or more; more preferably 10% or more; more preferably 20% or more;more preferably 40% or more. In dispersion feed embodiments, the totalamount of monomer in the feed composition is, by weight based on theweight of the feed composition, 60% or less; more preferably 55% orless.

In dispersion feed embodiments, it is useful to characterize the amountof multifunctional vinyl monomer as a weight percentage of the monomercontent of the feed composition. In dispersion embodiments, preferablythe amount of multifunctional vinyl monomer is, by weight based on thetotal weight of monomers in the feed composition, 50% to 100%; morepreferably 75% to 100%; more preferably 90% to 100%; more preferably 95%to 100%.

In dispersion feed embodiments, the suitable and preferable conditionsfor feeding during polymerization (extent of reaction, etc.) are thesame as those described above.

The present invention also involves a collection of polymeric beads. Thecollection of polymeric beads is preferably made by the method of thepresent invention. The polymeric beads contain polymer. Polymeric beadsare particles that are solid at 25° C. and that contain polymer in theamount, by weight based on the weight of the polymeric particles, of 90%or more; more preferably 95% or more.

The polymeric beads may be macroporous beads or gel beads. Preferred aregel beads.

Preferably the polymeric beads have volume average particle diameter of50 μm or larger; more preferably 100 μm or larger; more preferably 200μm or larger; more preferably 400 μm or larger. Preferably the polymericbeads have volume average particle diameter of 1,500 μm or lower; morepreferably 1,000 μm or lower.

Preferred polymers in the polymeric particles are the polymers formed byfree radical polymerization of the preferred vinyl monomers describedabove. Preferably the polymer contains polymerized units of styrenicmonomer in the amount, by weight based on the weight of the polymer, of5% or more; more preferably 25% or more; more preferably 50% or more;more preferably 75% or more; more preferably 95% or more. The types ofmonomers preferred as polymerized units of the polymer are the same asthose described above as preferred for use in the polymerizationprocess.

Preferred polymers have polymerized units of multifunctional vinylmonomer in an amount, by weight based on the weight of the polymer, of1% or more; more preferably 1.5% or more; more preferably 2% or more.Preferred polymers have polymerized units of multifunctional vinylmonomer in an amount, by weight based on the weight of the polymer, of25% or less; more preferably 20% or less; more preferably 15% or less;more preferably 11% or less; more preferably 6% or less.

Preferred polymers have polymerized units of monofunctional vinylmonomer in an amount, by weight based on the weight of the polymer, of99.7% or less; more preferably 99.5% or less; more preferably 99% orless; more preferably 98.5% or less. Preferred polymers have polymerizedunits of monofunctional vinyl monomer in an amount, by weight based onthe weight of the polymer, of 75% or more; more preferably 80% or more;more preferably 85% or more; more preferably 90% or more; morepreferably 94% or more.

The polymer in the polymeric bead has a relatively even distribution ofpolymerized units of multifunctional vinyl monomer. The uniformity ofthe distribution of polymerized units of multifunctional vinyl monomermay be characterized as follows.

-   -   MVAV=the average concentration (in moles per cubic micrometer)        of polymerized units of multifunctional vinyl monomer within a        single bead    -   T1000=a sequence of 1,000 connected polymerized monomer units    -   MVSEQ=for a specific T1000, the weight percent of polymerized        units of multifunctional vinyl monomer, based on the weight of        T1000    -   MVRATIO=MVSEQ/MVAV

In choosing a T1000, any polymerized unit may be chosen as the firstunit of the sequence. Then any polymerized unit that is covalentlybonded to the first polymerized unit may be chosen as the second unit inthe sequence. Similarly, each unit that is chosen is covalently bondedto the previous unit in the sequence. No polymerized unit may occurtwice in the T1000 sequence. When 1000 polymerized units have beenchosen, the T1000 sequence is complete. Another way to describe theprocess of selecting a T1000 is to state that a first polymerized unitis picked, and then a path is traced along covalently bonded polymerizedunits until the path is 1000 units long. The path is chosen so that itdoes not cross itself. Each bead contains many T1000 sequences. TheT1000 sequence is not physically altered or removed from the bead. TheT1000 sequence is a tool for characterizing the degree of uniformity ofa polymeric bead.

The bead is considered to be “uniform” if it has a relatively evendistribution of polymerized units of multifunctional vinyl monomer. Thatis, a bead is uniform if 90% or more, by number of sequences, of allT1000 sequences in the bead has MVRATIO of 1.5 or less. Preferred beadshave a higher degree of uniformity, such that 90% or more, by number ofsequences, of all T1000 sequences in the beads has MVRATIO of 1.25 orless.

In the collection of beads of the present invention, most of the beadsare uniform. That is, the amount of beads, by volume, that are uniformis 90% or higher; more preferably 95%% or higher; more preferably 99% orhigher. More preferably, the amount of beads, by volume, in which 90% ormore, by number of sequences, of all T1000 sequences has MVRATIO of 1.25or less is 90% or higher; more preferably 95% or higher; more preferably99% or higher.

It is useful to consider the percentage of T1000 sequences, by number ofsequences, that have MVRATIO of 0.5 or less. Preferably, 35% or less, bynumber of sequences, of the T1000 sequences will have MVRATIO of 0.5 orless. More preferably, 25% or less, by number of sequences, of the T1000sequences will have MVRATIO of 0.5 or less.

The polymeric beads preferably have average sphericity of 0.8 or higher;more preferably 0.85 or higher; more preferably 0.9 or higher; morepreferably 0.95 or higher.

A preferred use of the polymer produced in the free radicalpolymerization process of the present invention is to be used in aconversion process to produce an ion exchange resin. Ion exchange resinsfall into the following categories. Weak base anion exchange resins havependant amino groups that are primary, secondary, or tertiary. Strongbase anion exchange resins have pendant quaternary amino groups. Weakacid cation exchange resins have pendant carboxylic acid groups. Strongacid cation exchange resins have pendant sulfonic acid groups. When anyof these pendant functional groups have been attached to a polymer bead,the bead is referred to as a “functionalized resin.”

Typically, in the preparation of weak base anion exchange resins frompolymeric beads such as crosslinked polystyrene beads, the beads areadvantageously haloalkylated, preferably halomethylated, most preferablychloromethylated, and the ion active exchange groups subsequentlyattached to the haloalkylated copolymer. Typically, the haloalkylationreaction consists of swelling the crosslinked addition copolymer withhaloalkylating agent, preferably bromomethylmethyl ether,chloromethylmethyl ether, or a mixture of formaldehyde and hydrochloricacid, most preferably chloro-methylmethyl ether and then reacting thecopolymer and haloalkylating agent in the presence of a Friedel-Craftscatalyst such as zinc chloride, iron chloride, or aluminum chloride.Typically, a weak base anion exchange resin is prepared by reacting thehaloalkylated copolymer with ammonia, a primary amine, or a secondaryamine. Typically, a strong base anion exchange resin is prepared byreacting the haloalkylated copolymer with a tertiary amine.

Typically, in the preparation of strong acid cation exchange resins frompolymeric beads such as crosslinked polystyrene beads, the beads areadvantageously sulfonated. Generally, the bead is swollen using asuitable swelling agent and the swollen bead reacted with a sulfonatingagent such as sulfuric or chlorosulfonic acid or sulfur trioxide or amixture thereof.

A collection of functionalized polymeric beads normally contains waterin addition to the polymeric beads themselves. Normally, the processthat is used for making the functionalized polymeric beads involvescontact between the functionalized polymeric beads and water, and theexcess liquid water is removed, but a substantial amount of waterremains as part of the collection of functionalized polymeric beads. Itis contemplated that the water is adsorbed into the functionalizedpolymeric beads. The amount of water is typically 30% to 90% by weightbased on the weight of the collection of functionalized polymeric beads.

It is contemplated that the polymeric beads of the present inventionwould be useful for a variety of purposes. Functionalized polymericbeads would be useful for many of the purposes where ion exchange resinsare useful. For example, it is expected that the increased crushstrength and osmotic stability of the functionalized polymeric beads ofthe present invention would make these beads useful in the preferreduses as water-purification resins or as catalysts. When functionalizedpolymeric beads of the present invention are used as catalysts, it isexpected that the functionalized polymeric beads of the presentinvention would improve the reaction rate of the reaction beingcatalyzed. The uniformity of the spatial distribution of polymerizedunits of multifunctional vinyl monomer in the functionalized polymericbeads of the present invention is expected to have the effect that moreof the sites on the beads that are accessible for catalysis will alsohave the optimum concentration of polymerized units of multifunctionalmonomer for optimum reaction rate, as compared to previously-knownbeads.

Preferred methods of using the polymeric beads of the present inventioninvolve passing a liquid through a bed of the polymeric beads. That is,a collection of the polymeric beads is placed in a container that trapsthe polymeric beads in place, that has an inlet for a liquid to enterthe container, that allows the liquid to flow through the containerwhile making intimate contact with the polymeric beads, and that has anoutlet for the liquid to exit the container.

When the intended use is water purification, the functionalized resin isemployed to remove undesirable ions from the water. The resin hasfunctional groups (herein “functional groups (iii)”). The resin ischosen so that the functional groups (iii) have charge opposite to thecharge on the undesirable ion. Prior to the purification, the functionalgroups (iii) are associated with counterions (herein called “ions (iv)”)that are not bonded to the resin. Ions (iv) have the same charge as theundesirable ions. Preferably, the proportion of the functional groups(iii), on a molar basis, that is associated with ions (iv), is 50% ormore; more preferably 75% or more; more preferably 92% or more.

In a “loading” step, the water to be purified is passed through a bed ofthe resin, and the undesirable ions in the water load onto thefunctionalized polymeric bead by associating with the functional groups(iii), in exchange for the ions (iv). Eventually the resin becomesloaded at or near its capacity for retaining the undesirable ion. Then,to remove the undesirable resin, the functionalized polymeric beadundergoes a “regeneration” step in which a regeneration solution ispassed through the bed of resin. The regeneration solution containsdissolved ions including ions (v) that are the same species as ions(iv). The ions (v) replace the undesirable ions on the resin, and theundesirable ions are removed along with the regeneration solution.

Preferably, the cycle of loading and regeneration is repeated. That is,a new batch of water containing the same undesirable ion is passedthrough the bed of resin to load the resin with the undesirable ion, andthen the resin is regenerated as described above. Preferably, theprocess of loading and regeneration is repeated 10 or more times; morepreferably 20 or more times.

Repeated cycles of loading and regeneration causes osmotic shock to thefunctionalized polymeric bead, because equilibrium water content (andtherefore bead size) is a function of the specific counter ion. Repeatedcycles can cause some or all of the polymeric beads to break.Preferably, the polymeric beads of the present invention minimize suchbreakage.

The above discussion envisions a single undesirable ion of a certaincharge. If the water additionally contains a second undesirable ion ofopposite charge to the first undesirable ion, then it is envisioned thatthe water could be brought into contact with a second resin that hasfunctional groups of charge opposite to the charge on the functionalgroups on the first resin. The two resins may be used in sequence or maybe mixed together.

For example, a polymeric bead that is functionalized with sulfonic acidgroups is a strong acid cation exchange resin (“SAC”). An SAC could beused for removing unwanted sodium ions from water. At the outset, theSAC could be in hydrogen form. That is, more than half (on a molarbasis) of the sulfonate groups have counter ion H⁺. Then an aqueoussolution of NaCl could be passed through the bed of the SAC, to exchangethe hydrogen ions for sodium ions, so that the sodium ions are retainedon the SAC, putting the resin into sodium form, in a process called“loading” the resin. Eventually, the SAC reaches or approaches the limitof its ability to retain sodium ions. Then the SAC can be regenerated,for example by passing an aqueous solution of H₂SO₄ through a bed of theSAC, to put the resin back into hydrogen form. Such a cycle of loadingfollowed by regeneration puts the resin beads under osmotic pressure,because the sodium form and hydrogen form have different equilibriumwater content, and the osmotic shock of repeated cycles tends to breaksome of the beads.

For another example, a polymeric bead that is functionalized withquaternary ammonium groups is a strong base anion exchange resin(“SBA”). An SBA could be used for removing unwanted chloride ions fromwater. At the outset, the SBA could be in hydroxide form. That is, morethan half (on a molar basis) of the quaternary ammonium groups havecounter ion OH⁻. Then an aqueous solution of NaCl could be passedthrough the bed of the SBA, to exchange the hydroxide ions for chlorideions, so that the chloride ions are retained on the SBA, in a processcalled “loading” the resin. Eventually, the SBA reaches or approachesthe limit of its ability to retain chloride ions. Then the SBA can beregenerated, for example by passing an aqueous solution of NaOH througha bed of the SBA, to put the resin back into hydroxide form. Such acycle of loading followed by regeneration puts the resin beads underosmotic pressure, because the chloride form and the hydroxide form havedifferent equilibrium water content, and the osmotic shock of repeatedcycles tends to break some of the beads.

Analogous processes of loading and regenerating may be performed bythese or other resins for removing these or other ions. Weak acid cationexchange resins or strong acid cation exchange resins may be used forremoving either monovalent or multivalent cations. Weak base anionexchange resins or strong base cation exchange resins may be used forremoving unwanted monovalent and/or multivalent anions. Any of theseprocesses that involve loading and regenerating cycles create osmoticstress on the resin beads.

When the intended use is water purification, the resistance to crushingand the resistance to osmotic shock make the resins of the presentinvention advantageous. Because the beads have less tendency to break, agiven collection of beads will have a longer lifetime in use before thebeads need to be replaced. Also, when beads break, the fragments fill upthe interstitial spaces between the beads, which impedes the flow ofwater through the bed of beads, which causes increased pressure drop inthe water from the inlet of the bed to the outlet. Also, broken beadscan also cause channeling, which reduces the amount of water that thebed of beads can treat, thus making it necessary to regenerate the beadsmore often, which in turn increases chemical costs and increases theosmotic stress on the beads.

When the intended use of the resin is as a catalyst, the functionalizedcollection of polymeric beads, herein referred to as a “resin,” isemployed by bringing the resin into contact with one or more reactantsand allowing a chemical reaction to take place involving the one or morereactants, to produce one or more products. In a preferred catalystembodiment, the collection of polymeric beads is functionalized withsulfonic acid groups to produce an SAC. When used as a catalyst, the SACis referred to as an “acid catalyst.”

Resins that are intended for use as catalysts may be characterized bytheir moisture hold capacity (MHC). MHC is the amount of water presentin a collection of polymeric beads when bulk liquid water has beenseparated from the beads and the beads have been allowed to come toequilibrium with air having 100% relative humidity. Preferably, the MHCof resins intended for use as catalysts is, by weight based on the totalweight of the collection of resin beads, including the beads and thewater, is 90% or less; more preferably 80% or less. Preferably, prior tocontact with acetone and phenol, the amount of water present in theresin, by weight based on the weight of the resin, is 50% or more; morepreferably 60% or more.

Preferred reactants are acetone and phenol, reacting to make2,2-bis(4-hydroxyphenyl)propane (also called bisphenol A). It iscontemplated that two moles of phenol react with one mole of acetone tomake one mole of bisphenol A and one mole of water. In bisphenol Aformation, preferred resin catalysts are SAC resins. Prior to contactwith acetone and phenol, the resin may or may not be reacted with apromoter. In preferred embodiments, prior to contact with acetone andphenol, the resin is reacted with a promoter. Preferred promoters haveboth an amine group and a thiol group. Preferably, the amine groups onthe promoter attach to sulfonic acid groups on the resin. Preferably,the mole percent of sulfonic acid groups attached to an amine group of apromoter is 5% to 50%. Preferably, prior to contact with acetone andphenol, the water is removed from the collection of resin beads, forexample by rinsing with phenol. Preferably, immediately prior to contactwith acetone and phenol, the water content in the collection ofpolymeric beads is, by weight based on the collection of polymericbeads, 2% or less; more preferably 1% or less.

Preferably, while the resin is in contact with the phenol and theacetone, the resin is at temperature of 55° C. or higher; morepreferably 60° C. or higher.

When the intended use is catalysis, the resistance to crushing is alsoan advantage. The lifetime of resins of the present invention will behigher, and the reduced level of fine particles will enable reactants topass through the bed of resin with lower pressure drop.

The following are examples of the present invention.

The following terms, abbreviations, and materials were used:

-   Jetted=monomer droplets were introduced into the aqueous medium    using the jetting procedure described in U.S. Pat. Nos. 4,444,960    and 4,623,706-   tBC=4-t-butylcatechol; some tBC is present in the grade of DVB that    was used.-   DVB=divinylbenzene, produced and supplied by the Dow Chemical    Company. The grade of DVB that was used was a mixture that contained    63% pure divinylbenzene and approximately 37% ethylvinylbenzene by    weight. The percentages of DVB listed below refer to the amount of    pure DVB. When DVB is present, it is assumed that EVB is also    present in a weight ratio of EVB:DVB of approximately 37:63. DVB    contains approximately 1000 ppm by weight of tBC.-   tBC-free DVB=DVB that contains no tBC. To make tBC-free DVB, the tBC    was stripped from the portion of DVB indicated by a series of 4%    NaOH batch washes.-   CMMC=carboxymethyl methylcellulose, produced and supplied by The Dow    Chemical Co.-   PVOH=SELVOL™ 523 polyvinyl alcohol, from Sekisui Specialty Chemicals-   HEMC=WALOCEL™ MKX 15000 PF 01 hydroxyethyl cellulose, from the Dow    Chemical Company-   SBA=strong base anion exchange resin; copolymer of styrene/DVB    functionalized with quaternary ammonium groups-   SAC=strong acid cation exchange resin; copolymer of styrene/DVB,    functionalized sulfonic acid groups-   Tris=tris(hydroxymethyl)aminomethane, 100% solid supplied by Fisher    Scientific, used as 20% by weight solution in water-   PADMAC=solution in water of 20% by weight poly(diallyldimethyl    ammonium chloride), also called poly(DADMAC).-   gelatin=animal based gelatin, isoelectric point approximately 8.5-   VPBA=4-vinylphenyl boronic acid-   BPO=benzoyl peroxide, 75% purity by weight-   DI water=deionized water-   Dichromate: =sodium dichromate dihydrate solution, concentration=70%    dihydrate in water by weight-   GA=gradual addition-   ambient temperature=approximately 23° C.

Eight protocols for suspension polymerization were used, labeled A, B,D, E, F, G, and H. The protocols are distinguished by the parameters asfollows. After copolymer beads were formed, they were functionalizedusing the method listed in the final column. The details of thefunctionalization methods are shown below the table.

polymer⁽¹⁾ inhibitor⁽²⁾ formation⁽³⁾ total DVB⁽⁴⁾ functionalization ACMMC + PVOH NaNO₂ jetted 4.65% sulfonation B CMMC + PVOH NaNO₂ jetted5.2%  sulfonation C CMMC + PVOH NaNO₂ jetted 4.65 to 5.2%  sulfonation DCMMC + PVOH NaNO₂ jetted 2.0 to 2.8% sulfonation E PADMAC + gelatinNaNO₂ jetted 4.65% sulfonation F CMMC + PVOH NaNO₂ jetted  9.2 to 11.0%sulfonation G HEMC dichromate agitation 7.6 to 9.0% sulfonation HPADMC + gelatin NaNO₂ jetted 4.65% CM/A ⁽¹⁾Water-soluble polymer in theaqueous medium ⁽²⁾Inhibitor in the aqueous medium ⁽³⁾Whether thedroplets are formed by jetting or by agitation ⁽⁴⁾The total amount byweight percentage of DVB in the entire process, as a percentage of totalmonomer weight.

In preparation of the droplet mixtures or the aqueous media describedbelow, some partial mixtures were sometimes heated above 25° C. toachieve good mixing. However, at the time when the droplets were formedand suspended in the aqueous medium, all the ingredients were at ambienttemperature.

Where copolymers were converted to SAC resins, the copolymer-containingpolymeric beads were sulfonated by standard sulfonation processes, usingsulfuric acid, to achieve a degree of substitution such that at least 95mole % of aromatic rings on polymerized units of monofunctional vinylmonomer, based on the total polymerized units of monofunctional vinylmonomer, had a sulfonate group.

Crush Strength was measured as follows. Functionalized polymeric beadswere placed into contact with air at 100% humidity at 50° C. for 4 days.Then the beads were covered with deionized water and stored for one houror more at room temperature (approximately 23° C.). A single bead wasplaced on one plate of a compression tester at room temperature, and thebead was covered with one drop of water. The plates are brought togetherat 6.0 mm/min until the particle fractures, and the peak force is noted.The procedure is repeated for at least 30 beads, and the average peakforce is reported as the “crush strength.” The test apparatus was aChatillon™ force tester model TCD 200, with a medium-slow motor (2.5 to63.5 mm/min). Force gauge was model DFGS10. Crush strength is reportedin grams of force per bead (g/bd).

Osmotic stability (OS) was measured as follows. Functionalized polymericbeads were conditioned by contact with a solution of NaCl in water atambient temperature (approximately 23° C.). The NaCl solution wasdecanted, and the wet resin was passed through mesh screens to produce asample of resins having diameter of 500 μm to 710 μm. Then resin wasplaced in a vertical straight-walled glass column. A single cycle was asfollows: fluid drained from the column by gravity; resin in the columnwas contacted with solution #1; the column was backwashed with water;fluid drained from the column by gravity; resin in the column wascontacted with solution #2; the fluid was drained from the column, thecolumn was backwashed with water. The test was repeated for 50 cycles.Solution #1 was H₂SO₄ in water. Solution #2 was NaOH in water. Thecycles of exposure to different solutions causes some particles tobreak. After the cycles of exposure, the beads were placed on a screenthat passes objects of diameter less than 500 μm. The material retainedon the screen is considered to be whole beads, and the material passingthrough the screen is considered to be fragments of broken beads. Theosmotic stability is

OS (%)=100×W _(frag)/(W _(whole) +W _(frag))

where W_(frag)=weight of fragments, and W_(whole)=weight of whole beads.Lower OS values are more desirable.

Functionalized resin samples were tested for storage stability asfollows. Resin was separated from bulk water and brought intoequilibrium with air at ambient temperature and 100% relative humidity.Resin was then placed in a closed vial and stored for 30 days at ambienttemperature. Then the resin was thoroughly mixed with DI water in aweight ratio of 3 parts water to 1 part resin. Water was removed byfiltration, and the water was tested for conductivity and for absorbanceat wavelength of 350 nm, using standard instruments.

In all protocols except G, the weight ratio of droplet ingredients toaqueous phase ingredients was 0.61:1. In protocol G, the weight ratio ofdroplet ingredients to aqueous phase ingredients was 1:1. When DVB wasgradually added during polymerization, the addition was continuous overthe extent range shown in the table in Example R1 below. DVB addition,while continuous, varied in rate during the course of the addition.

The compositions of the starting droplets (immediately prior to theinitiation of polymerization) in the following examples were as follows.Amounts are % by weight based on the weight of the monomer droplets.(All samples with the same prefix used the same composition of aqueousmedium. For example, all of examples A-2a(1), A-2a(2), and A-2b used thesame aqueous medium composition, labeled “A-2”). Total weight of eachmonomer droplet composition was 10000. Samples with suffix “Comp” areused in comparative methods. BPO as initiator was present in allstarting droplets.

Example DVB Stabilizer Aid t-BC-free DVB Styrene A-1Comp 4.65 VPBA 0balance A-2a 2.0 VPBA 0 balance A-2b 2.0 VPBA 0 balance A-2c 0.8 VPBA 0balance B-1Comp 2.25 none 2.95 balance B-2 2.25 none 0 balance C-1Comp4.65 none 0 balance C-2 2.25 none 0 balance D-1Comp 2.0 VPBA 0 balanceD-2a 0.8 none 0 balance D-2b 1.1 none 0 balance

Example DVB Stabilizer Aid Styrene E-1 4.65 none balance E-2 2.0 nonebalance F-1 9.2 VPBA balance F-2 4.65 none balance G-1 7.6 none balanceG-2 3.9 none balance

The compositions of the aqueous media in the following examples were asfollows. Amounts are % by weight based on the weight of the aqueousmedium. In all cases, the aqueous phase concentration of stabilizers wassuch that the number percentage of beads having sphericity of 0.8 orhigher was at least 99%, based on the total number of beads. In allcases, the aqueous or monomer phase concentration of stabilizer was suchthat the number percentage of having sphericity of 0.8 or higher was atleast 99%, based on the total number of beads. In all cases, the aqueousphase concentration of latex inhibitor was such that the weightpercentage of emulsion polymer at the end of the reaction was less than0.5%, based on the total weight of polymeric beads.

The harmonic mean diameter of the final polymer beads formed by jettingwas 430-470 micrometers. For droplets formed by agitation, the harmonicmean diameter of the final polymer beads was 490-650 micrometers.

Example Stabilizer Latex Inhibitor Stabilizer Aid A-1Comp CMMC + PVOHNaNO₂ none A-2 CMMC + PVOH NaNO₂ none B-1 Comp CMMC + PVOH NaNO₂ VPBAB-2 CMMC + PVOH NaNO₂ VPBA C-1 Comp CMMC + PVOH NaNO₂ VPBA C-2 CMMC +PVOH NaNO₂ VPBA D-1 Comp CMMC + PVOH NaNO₂ none D-2 CMMC + PVOH NaNO₂VPBA

Example Stabilizer Latex Inhibitor E-1Comp Gelatin + PADMAC NaNO₂ E-2Gelatin + PADMAC NaNO₂

Example Stabilizer Latex Inhibitor Stabilizer Aid F-1Comp CMMC + PVOHNaNO₂ none F-2 CMMC + PVOH NaNO₂ VPBA G-1Comp HEMC Dichromate none G-2HEMC Dichromate none

Comparative Example A1-Comp (No Addition of Monomer after Initiation ofPolymerization), Using Protocol A

Aqueous suspension polymerization was conducted on the reaction mixtureas follows. A combination of reaction temperature and BPO concentrationwas chosen to result in an extent of conversion of 80-85% within 330-390minutes. Once conversion to polymer was in the 80-85% range, pH wasadjusted by Tris addition to the reactor—such that the final pH was inthe 8-9 range. The reaction system was heated to 97° C. After 1 hour at97° C., the system was cooled to ambient temperature and the beads weredewatered, washed with water, and dried at ambient temperature. Twoidentical polymerizations were conducted.

Example A-2a and A-2b, Also Using Protocol A

Aqueous suspension polymerization was conducted on the reaction mixtureas follows. A combination of reaction temperature and BPO concentrationwas chosen to result in an extent of conversion of 80-85% within 390-550minutes. Once reaction temperature was reached, DVB was fed to thereactor, over the extent range shown in the table in Example R1 below,with the DVB feed rate varying with time. Two duplicate polymerizationsof A-2a were performed, labeled A-2a(1) and A-2a(2).

Once conversion to polymer was in the 60-75% range, Tris was added tothe reactor, such that the final pH was in the range of 8-9. Thereaction system was heated to 97° C. within 60 minutes of Tris addition.After 1 hour, the system was cooled to ambient temperature and the beadswere dewatered, washed with water and dried at ambient temperature.

Example A-2c, Also Using Protocol A

Aqueous suspension polymerization was conducted on the reaction mixtureas follows. A combination of reaction temperature and BPO concentrationwas chosen to result in an extent of conversion of 80-85% within 390-550minutes Once reaction temperature was reached, DVB was fed to thereactor, over the extent range shown in the table in Example R1 below,with the DVB feed rate varying with time.

Once conversion to polymer was in the 60-75% range, Tris was added tothe reactor, such that the final pH was in the 8-9 range. The reactionsystem was heated to 97° C. within 60 minutes of the Tris addition.After 1 hour, the system was cooled to ambient temperature and the beadswere dewatered, washed with water and dried at ambient temperature.

Comparative Example B1-Comp (No Addition of Monomer after Initiation ofPolymerization), Using Protocol B

Aqueous suspension polymerization was conducted on the reaction mixtureas follows. A combination of reaction temperature and BPO concentrationwas chosen to result in an extent of conversion of 80-85% within 480-560minutes. Once at reaction temperature, a feed of 0.1% tBC in water tothe reactor was started. The tBC feed rate varied with time, to simulatethe tBC feed that would normally accompany a DVB feed.

tBC was gradually added from Extent 0% to 57%. Prior to initiation ofpolymerization, tBC concentration in the monomer droplets was 0.0055% byweight. At the end of the tBC feed, the tBC concentration in the monomerdroplets (partially or fully converted to polymer) was 0.0101% byweight.

Once conversion to polymer was in the 80-85% range, pH was adjusted byTris addition to the reactor, such that the final pH was in the range of8-9. The reaction system was heated to 97° C. After 1 hour, the systemwas cooled to ambient temperature and the beads were dewatered, washedwith water, and dried at ambient temperature.

Examples B-2a, B-2b, B-2c, B-2d, B-2e, and B-2f, Also Using Protocol B

Duplicate samples of B-2b were made, labeled B-2b(1) and B-2b(2).

Aqueous suspension polymerization was conducted on the reaction mixtureas follows. A combination of reaction temperature and BPO concentrationis chosen to result in an extent of conversion of 80-85% within 420-600minutes. Once reaction temperature was reached, DVB was fed to thereactor, over the extent range shown in the table in Example R1 below,with the DVB feed rate varying with time.

Once conversion to polymer was in the 60-85% range, Tris was added tothe reactor, such that the final pH was in the 8-9 range. The reactionsystem was heated to 97° C. within 60 minutes of the Tris addition.After 1 hour, the system was cooled to ambient temperature and the beadswere dewatered, washed with water and dried at ambient temperature.

Comparative Example C1-Comp (No Addition of Monomer after Initiation ofPolymerization), Using Protocol C

Aqueous suspension polymerization was conducted on the reaction mixtureas follows. A combination of reaction temperature and BPO concentrationis chosen to result in an extent of conversion of 80-85% within 330-390minutes. Once reaction temperature was reached, Tris was added to thereactor such that the final aqueous pH was in the 8-9 range. Onceconversion was in the 80-85% range, the system was heated to 97 C. After1 hour at 97° C., the system was cooled to ambient temperature and thebeads were dewatered, washed with water, and dried at ambienttemperature.

Example C-2, Using Protocol C

Aqueous suspension polymerization was conducted on the reaction mixtureas follows. A combination of reaction temperature and BPO concentrationis chosen to result in an extent of conversion of 80-85% within 420-600minutes. Once reaction temperature was reached, DVB was fed to thereactor, over the extent range shown in the table in Example R1 below,with the DVB feed rate varying with time.

Once conversion was in the 60-85% range, Tris was added to the reactorsuch that the final pH was in the 8-9 range. The reaction system washeated to 97° C. within 60 minutes of the Tris addition. After 1 hour,the system was cooled to ambient temperature and the beads weredewatered, washed with water and dried at ambient temperature.

Comparative Example D1-Comp (No Addition of Monomer after Initiation ofPolymerization), Using Protocol D

Aqueous suspension polymerization was conducted on the reaction mixtureas follows. A combination of reaction temperature and BPO concentrationis chosen to result in an extent of conversion of 80-85% within 420-600minutes. Once conversion to polymer was in the 80-85% range, pH wasadjusted by Tris addition to the reactor—such that the final pH is inthe 8-9 range. The reaction system was heated to 97° C. After 1 hour,the system was cooled to ambient temperature and the beads weredewatered, washed with water, and dried at ambient temperature. Twoidentical polymerizations were conducted.

Example D-2a, Using Protocol D

Aqueous suspension polymerization was conducted on the reaction mixtureas follows. A combination of reaction temperature and BPO concentrationis chosen to result in an extent of conversion of 80-85% within 390-550minutes. Once reaction temperature was reached, DVB was fed to thereactor, over the extent range shown in the table in Example R1 below,with the DVB feed rate varying with time. Two duplicate polymerizations,labeled D-2a(1) and D-2a(2), were performed.

Once conversion to polymer was in the 20-30% range, Tris buffer wasadded to the reactor, such that the final pH was in the 8-9 range.Additional Tris buffer was added when conversion reached 80-85% suchthat the final pH was in the range of 8-9. The reaction system was thenheated to 97° C. within 60 minutes of the Tris addition. After 1 hour,the system was cooled to ambient temperature and the beads weredewatered, washed with water and dried at ambient temperature.

Example D-2b, Using Protocol D

The same protocol as in D-2a was used, except that DVB was graduallyadded over the extent range shown in the table in Example R1 below. Twoduplicate polymerizations, labeled D 2b(1) and D-2b(2), were performed.

Comparative Example E-1Comp (No Addition of Monomer after Initiation ofPolymerization), Using Protocol E

Aqueous suspension polymerization was conducted on the reaction mixtureas follows. A combination of reaction temperature and BPO concentrationis chosen to result in an extent of conversion of 80-85% within 210-270minutes. Once conversion to polymer was in the 80-85% range, thereaction system was heated to 92° C. After 1 hour, the system was cooledto ambient temperature and the beads were dewatered, washed with water,and dried at ambient temperature.

Example E-2, Using Protocol E

Aqueous suspension polymerization was conducted on the reaction mixtureas follows. A combination of reaction temperature and BPO concentrationis chosen to result in an extent of conversion of 80-85% within 300-360minutes. Once reaction temperature was reached, DVB was fed to thereactor, over the extent range shown in the table in Example R1 below,with the DVB feed rate varying with time.

Once conversion to polymer was in the 80-85% range, the reaction systemwas heated to 92° C. After 1 hour, the system was cooled to ambienttemperature and the beads were dewatered, washed with water and dried atambient temperature.

Comparative Example F1-Comp (No Addition of Monomer after Initiation ofPolymerization), Using Protocol F

Aqueous suspension polymerization was conducted on the reaction mixtureas follows. A combination of reaction temperature and BPO concentrationis chosen to result in an extent of conversion of 80-85% within 300-360minutes. Once conversion to polymer was in the 80-85% range, pH wasadjusted by Tris addition to the reactor—such that the final pH is inthe 8-9 range. The reaction system was heated to 97° C. After 1 hour,the system was cooled to ambient temperature and the beads weredewatered, washed with water, and dried at ambient temperature.

Example F-2, Using Protocol F

Aqueous suspension polymerization was conducted on the reaction mixtureas follows. A combination of reaction temperature and BPO concentrationis chosen to result in an extent of conversion of 80-85% within 330-390minutes. Once reaction temperature was reached, tBC-free DVB was fed tothe reactor, over the extent range shown in the table in Example R1below, with the DVB feed rate varying with time.

Once conversion to polymer was in the 80-85% range, Tris was added tothe reactor, such that the final pH was in the 8-9 range. The reactionsystem was heated to 97° C. within 60 minutes of the Tris addition.After 1 hour, the system was cooled to ambient temperature and the beadswere dewatered, washed with water and dried at ambient temperature.

Comparative Example G1-Comp (No Addition of Monomer after Initiation ofPolymerization), Using Protocol G

Aqueous suspension polymerization was conducted on the reaction mixtureas follows. A combination of reaction temperature and BPO concentrationis chosen to result in an extent of conversion of 80-85% within 300-360minutes. Once conversion to polymer was in the 80-85% range, thereaction system was heated to 90 C. After 3 hours, the system was cooledto ambient temperature and the beads were dewatered, washed with waterand dried at ambient temperature.

Example G-2, Using Protocol G

Aqueous suspension polymerization was conducted on the reaction mixtureas follows. A combination of reaction temperature and BPO concentrationwas chosen to result in an extent of conversion of 80-85% within 420-600minutes. Once reaction temperature was reached, DVB was fed to thereactor, over the extent range shown in the table in Example R1 below,with the DVB feed rate varying with time.

Once conversion to polymer was in the 80-85% range, the reaction systemwas heated to 90 C. After 3 hours, the system was cooled to ambienttemperature and the beads were dewatered, washed with water and dried atambient temperature.

Example R1: Results of Physical Stability Testing SAC Resins

Copolymers made with the above protocols were converted to SAC resinsand tested as described above. Results were as follows. Where duplicatesamples were tested, the average results are shown.

-   method=refers to whether the polymerization method had the gradual    addition (GA) step of the present invention or not.-   init DVB=the amount of DVB in the monomer droplets prior to    initiation of polymerization, (by weight based on the weight of the    monomer droplets)-   final DVB=the amount of polymerized units of DVB in the finished    polymer, by weight based on the total weight of all monomer used in    the entire process, including the initial droplets and the DVB fed    during polymerization-   EXTSTART=extent of reaction at which DVB feed was begun-   EXTSTOP=extent of reaction at which DVB feed was ended-   DIAM=harmonic mean diameter of polymeric beads

init final EXT- EXT- DVB DVB START STOP DIAM Crush OS Example method (%)(%) (%) (%) (μm) (g/bd) (%) A-1Comp no GA 4.65 4.65 none none 450 80612.4 A-2a GA 2 4.65 0 60 450 3242 1.8 A-2b GA 2 4.65 0 85 450 2882 2.7A-2c GA 0.8 4.65 0 58 450 2458 1.1 B-1Comp no GA 5.2 5.2 none none 4501375 1.7 B-2a GA 2.25 5.2 0 78 450 3271 1.6 B-2b GA 2.25 5.2 0 59 4503649 1.2 B-2c GA 2.25 5.2 0 24 450 3736 0.6 B-2d GA 2.25 5.2 0  5 4504215 0.4 B-2e GA 2.25 5.2 15  43 450 2700 0.4 B-2f GA 2.25 5.2 27  33450 2673 0.7 C-1Comp no GA 4.65 4.65 none none 450 838 13.8 C-2 GA 2.255.2 0 62 450 2646 2.7 D-1Comp no GA 2.0 2.0 none none 450 916 11.1 D-2aGA 0.8 2.0 0 74 or 75 450 1470 2.3 D-2b GA 1.1 2.8 0 80 or 85 450 17732.0 E-1Comp no GA 4.65 4.65 none none 460 830 17.2 E-2 GA 2.0 4.65 0 80460 1044 3.9 F-1Comp no GA 9.2 9.2 none none 450 2125 0.4 F-2 GA 4.6511.0 0 67% 450 3412 0.1 G-1Comp no GA 7.6 7.6 none none 450 560 8.6 G-2GA 450 2420 1.4

Example R2: Results of Testing of Samples of Protocol E

From the copolymers of protocol E, Strong Base Anion (SBA) exchangeresins were made by a standard process of chloromethylation usingchloromethyl ether followed by amination using trimethyl amine, suchthat at least 95 mole of aromatic rings on polymerized units ofmonofunctional vinyl monomer, based on the total polymerized units ofmonofunctional vinyl monomer, had an amine-containing group attached.

The SBA resins were tested as in Example A-R. Results were as follows:

init final EXT- EXT- DVB DVB START STOP DIAM Crush OS Example method (%)(%) (%) (%) (μm) (g/bd) (%) H-1Comp no GA 4.65 4.65 none none 450 16053.8 H2 GA 2.0 4.65 0 80% 450 324 37.0

Example R3: Results of Catalysis

Various functionalized resin samples were tested for activity incatalyzing the reaction between phenol and acetone to make bisphenol-A(BPA). The catalytic activity is characterized by the time to 60%conversion (“T60%”). Shorter times reflect higher level of catalyticactivity.

The catalysis reactions were carried out as follows: Resin was rinsedwith phenol to remove moisture from the beads. Phenol was added to aglass reactor and heated at 50° C. to melt the phenol. Dry resin, loadedwith promoter, was added to the reactor and allowed to swell in thephenol. Reactor temperature was regulated at a temperature between 45°C. and 80° C. Acetone was added to the reactor. At time intervals, asmall sample of the liquid in the reactor was removed by pipette, placedin a vial, and mixed with excess N-Methyl-N-(trimethylsilyl)trifluoroacetamide. Vials were stored for 30 minutes at 60° C., thencooled to ambient temperature, then tested by Gas Chromatography for BPAcontent.

The catalysis results were as follows. All of the samples shown hadtotal amount of polymerized units of DVB of 4.65%.

Example A-2a A-2b A-2c C-1Comp T60% (min) 52 52 47 71

Samples A-2a, A-2b, and A-2c, which were made using gradual additionaccording to the present invention, had much shorter times to 60%conversion than the comparative sample.

Example R4: Results of Storage for 30 Days at Ambient Temperature

Storage results were as follows:

Example: A-1Comp A-2a A-2b C-1Comp C-2 Conductivity (μS) 169 127 160 189126 Absorbance 0.225 0.165 0.171 0.235 0.137

Each Example resin showed lower conductivity and absorbance than itscorresponding comparative example. That is, samples A-2a and A-2b showedlower conductivity and absorbance than comparative A-1Comp. Similarly,sample C-2 showed lower conductivity and absorbance than comparativeC-1Comp. This result shows that the Example resins have greaterstability during storage.

1. A process of making a collection of polymeric beads, wherein thebeads comprise (i) 75 to 99% by weight, based on the weight of the bead,polymerized units of monofunctional vinyl monomer, and (ii) 1 to 25% byweight, based on the weight of the bead, polymerized units ofmultifunctional vinyl monomer; wherein the process comprises (a)providing an aqueous suspension of monomer droplets comprisinginitiator, monofunctional vinyl monomer and multifunctional vinylmonomer; (b) initiating polymerization of the monomer in the monomerdroplets; (c) while the polymerization of the monomer in the monomerdroplets is occurring, adding a monomer feed solution to the suspension,wherein the adding begins at a time when the extent of polymerization ofmonomer in the monomer droplets (EXTSTART) is 0% to 50%, and wherein theadding ends at a time after EXTSTART when the extent of polymerizationof monomer in the monomer droplets (EXTSTOP) is 5% to 100%; wherein thefeed solution comprises monomer in an amount, by weight based on theweight of the feed solution, of 90% to 100%; wherein the feed solutioncomprises multifunctional vinyl monomer in an amount, by weight based onthe weight of the feed solution, of 50% to 100%.
 2. The process of claim1, wherein a quantity EXTDIF=EXTSTOP−EXTSTART is 5% or more.
 3. Theprocess of claim 1, wherein the monofunctional vinyl monomer comprisesstyrene.
 4. The process of claim 1, wherein the multifunctional vinylmonomer comprises divinylbenzene.
 5. A process of making a collection ofpolymeric beads, wherein the beads comprise (i) 75 to 99% by weight,based on the weight of the bead, polymerized units of monofunctionalvinyl monomer, and (ii) 1 to 25% by weight, based on the weight of thebead, polymerized units of multifunctional vinyl monomer; wherein theprocess comprises (a) providing an aqueous suspension of monomerdroplets comprising initiator, monofunctional vinyl monomer andmultifunctional vinyl monomer; (b) initiating polymerization of themonomer in the monomer droplets; (c) while the polymerization of themonomer in the monomer droplets is occurring, adding a monomer feedcomposition to the suspension, wherein the adding begins at a time whenthe extent of polymerization of monomer in the monomer droplets(EXTSTART) is 0% to 50%, and wherein the adding ends at a time afterEXTSTART when the extent of polymerization of monomer in the monomerdroplets (EXTSTOP) is 5% to 100%; wherein the feed composition comprisesmonomer dispersed in an aqueous medium; wherein the feed compositioncomprises multifunctional vinyl monomer in an amount, by weight based onthe total weight of monomer in the feed composition, of 50% to 100%.